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Topic: [HM] Bombelli: Cube root of Complex Nos.
Replies: 8   Last Post: Feb 19, 2001 5:31 AM

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Bonnie Shulman

Posts: 20
Registered: 12/3/04
Re: [HM] Bombelli: Cube root of Complex Nos.
Posted: Feb 14, 2001 1:53 PM
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Oops, so sorry! cos(arctan 11/2) would not be hard to find.
What I meant to write was cos[(arctan 11/2)/3]. And, indeed,
as one quickly realizes, this leads to the angle-tripling formula
(4 cos^3 x - 3 cos x = cos 3x). And, indeed, circularly, one
basically ends up with one's original cubic!

--Bonnie Shulman

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